The second section on integrals has arrived! The section covers three additional methods of estimating integrals using finite sums: the midpoint method, the trapezoid rule, and Simpson's rule. The section on Simpson's rule features an exhaustive derivation of the formula, although an explanation of Lagrange interpolation is saved for later. The derivation is provided more for completeness than as an actual practice problem, as its absence would have bothered me. While knowledge of solving integrals analytically is technically required to understand how Simpson's rule works, it is nonetheless grouped with the other estimation methods in keeping with the general theme.